1. Technical Field
This invention relates to a process, a plant, and a biofuel for integrated biofuel production, such as with butanol, biodiesel, and/or sugar product.
2. Discussion of Related Art
Tightening oil supply and escalating energy prices along with environmental concerns over nonrenewable resources have prompted significant interest and research into alternative fuels. Efforts to reduce carbon emissions and greenhouse gases are also driving investment into alternative fuels.
Anderson et al., U.S. Patent Application Publication 2008/0227182 discloses systems and methods for enzymatic hydrolysis of lignocellulosic materials. The enzymatic hydrolysis converts hexose sugars from cellulose and pentose sugars from hemicellulose. The system produces a mixed stream of 6-carbon sugars and 5-carbon sugars and then seeks to ferment them to ethanol with a microorganism capable of fermenting both glucose and xylose to ethanol. Anderson et al. does not disclose segregated 6-carbon sugar and 5-carbon sugar processes.
McKeeman et al., U.S. Patent Application Publication 2008/0050800, discloses a method and apparatus for a multi-system bioenergy facility. The multi-system bioenergy facility generates electricity with biogas from an anaerobic digester and ethanol from an ethanol production facility. The multi-system bioenergy facility also generates triglycerides with algae from bioreactors supplied with nutrient rich waste water from the anaerobic digester and carbon dioxide rich flue gas from a steam production facility. McKeeman et al. does not disclose a sugar to biodiesel method or apparatus.
Aare, U.S. Patent Application Publication 2007/0099278, discloses production of biodiesel from a combination of corn (maize) and other feed stocks. The process separates corn oil and corn starch which is enzymatically converted to fermentable sugars with a liquification and saccharification process. Yeast is added to ferment the sugars before distillation to produce ethanol. The corn oil is fed into a transesterification vessel where ethanol with catalyst forms crude biodiesel and crude glycerin. The amount of biodiesel is limited to the small amount of oil in the corn. Aare does not disclose a sugar to biodiesel process.
However, even with the above improvements in the processes, there is a need and a desire to coproduce biodiesel with butanol and/or sugar product in a manner that is less expensive and more integrated than known processes. There is also a need and a desire to maintain separated biological pathways for hexose conversion and pentose conversion.